DHES

OK so all of your store is in these series of files (store.pos, store.tbl, etc.)

At my work, in the morning, the server runs this app that checks
the files on the tills against the files on the server.
This is primarily b/c any register will work without the server
and the server, at POS open or POS close has to make sure there
weren't any 'offline' sales.
The way it works is to have a copy of the "system" (all the store files)
on each till and that way if the server goes down - and it does a lot-
you can still run your store. The stock table is kept on one specific
register and when the server goes down, you log onto this particular
register and go into the menu and 'disable server route; enable backup' what this does is makes this till the new server for awhile and tells the
registers (perhaps in a manner such as that of the remote.exe prog)
to use it as the server. All in all, if you know you are switching over
it only hangs the regaisters for a few seconds. During this few seconds,
it downloads onto itself all the files on the server then tells the tills that
it is the server. This is really not at all unrealistic in DHPOS. It would
just be a bunch of batch files and a network comm. program.

Anyway, so at POS open, the server compares its files to that master register
and if there is a descrepency it'll ask you which copy to keep, then
it overwrites the other and continues to open the system.